Mine protective device



Sept. 19, 1961 L, R, |TTLET0N 3,000,302

MINE PROTECTIVE DEVICE Filed March 22, 1960 1N V EN TOR.

Leunida's RLiHlEn'n United States Patent() 3,000,302 MINE PROTECTIVEDEVICE Leonidas R. Littleton, Emory, Va., assignor to the United Statesof America as represented by the Secretary of the Army Filed Mar. 22,1960, Ser. No. 16,897 1 Claim. (Cl. 102--8) (Granted under Title 35,U.S. Code (1952), sec. 266) The invention described herein may bemanufactured and used by or `for the Government for governmentalpurposes without the payment to me of any royalty there- The presentinvention relates to mine protective devices and more particularly to amine fuze which will not be detonated by a suddenly applied force, butwhich will be detonated upon the application of gradually appliedpressure.

Land mines have become an integral part of defensive land warfare,materially hindering the advance of enemy infantry or vehicles andaffording protection for retreating forces. Mine fields must be clearedbefore the attacking force can advance.

Various methods have been devised to clear an area of mines. One methodis to spread over the area explosives in various forms and then detonatethem to actuate the mine `fuzes. Another method is to drop shells orbombs into the mined area. Yet another method which has been partiallysuccessful is to push a rotating fiail over the field which beats theground in front of the machine and detonates the mines.

It will be seen that in each of the above noted clearing methods,detonation of the mine is caused by a sudden impact of short duration.Thus, it will be seen that if the mine is provided with a fuze whichresponds to a gradually applied pressure such as would be caused byvehicles or troops, but not to a sudden impact of short duration, a Veryeffective mine which Would be difficult to clear would be obtained.

My invention comprises a device which is placed over the land minecontaining a plunger or trigger which upon being depressed will strikethe fuze mechanism and activate it. The plunger or trigger is restrainedby uid pressure such that it will not be depressed by a sudden impulse,but will be depressed by a gradually applied pressure.

It is an object of this invention to provide a mine having a fuze whichwill be sensitive to gradually applied pressure, but insensitive to asuddenly applied impulse.

Another object is to provide a mine having a fuze actuating pressureplate, the movement of the pressure plate being resisted by fluidpressure.

These and other objects will become more apparent when reference is hadto the following detailed description and drawing in which:

The iigure is an axial sectional view of the mine protective device andmine with the mine being shown fragmentarily.

Referring now to the drawing there is shown the upper portion of a landmine 1 which is provided with fuze 2 by which the mine is detonated. Theupper surface of the mine is provided with an annular iiange 3 forreceiving the mine protective device to be described.

The mine protective device is generally indicated at 4 and comprises abody having the outer cylindrical wall 5 received in the flange 3r onthe mine. The body is further provided with inner annular Wall 6 andintermediate annular wall 7. The end wall 8 connects all three walls 5,6 and 7 and end Wall 9 connects walls 5 and 7. Thus, there is formed anannular outer chamber 10 and an annular inner chamber 11. The chamber 10may be vented near the top if desired as shown at 20` Mice Apertures 12are provided in the Wall 7 to provide restrlcted communication betweenthe chambers 10 and 11. The inner wall 6 defines a central passage 13through 4the body and the lower end of this passage is provided with aguide sleeve 14. A quantity of hydraulic iiuid is supplied to the twochambers 10 and 11 as indicated on the drawing. An annular iioatingpiston 15 is provided and is of such size as to slidably contact theWalls 6 and 7. This piston rests on the top of the liquid in chamber 11.Seals may be provided between the piston 1S and walls 6 and 7 ifdesired. Connected to or resting on the top of piston 15 is the cupshaped pressure plate 16 having flange'17 which ltelescopes with theoutside of wall 5. An actuating pin 18 is connected to pressure plate 16and is slidably received in sleeve 14. Spring 19 surrounds the pin 18and reacts between the sleeve 14 and pressure plate 16 to urge the plateupward. It will be seen that this spring could be omitted if desired ifthe chamber 10 1s not vented, as the air in the chamber 10 would thenform an air spring.

Operation It will be seen that the parts will have an equilibriumposition as shown in the drawing with the spring 19 counterbalancing theweight of the piston 15 and pressure plate 16 with the actuating pinspaced from the fuze 2.

If a sudden shock or impulse of short duration occasioned by one of thepreviously noted mine clearing methods is applied to the pressure platethe mine will not detonate. Such a force would be transmitted throughthe piston 15 to the incompressible hydraulic liuid. In View of therestricted size and small number of orifices 12, iiuid transfer fromchamber 11 to chamber 10 wil-l be slow and the force from the shock orimpulse ceases before sufficient fluid ow has occurred to permit theactuating pin 18 to operate the fuze 2. After the impulse the spring 19returns the pressure plate to normal positlon.

If now the pressure plate is actuated by personnel or equipment comingin contact therewith, a force is applied thereto which is relatively ofmuch longer duration. Under these circumstances the pressure is appliedyfor a sufiicient length of time for enough iiuid to pass from chamber11 to chamber 10 to permit the actuating pin 1S to contact and operatefuze 2. The sensitivity can be varied by changing the total area of theorifices 12 and varying the strength of spring 19.

It is to be noted that the shape of the annular cylinders and pressureplate need not be circular, but may be square, oval or any other shapedictated by the particular application. The term annular as used `in thespecification and claim is intended to cover these various shapes.

The hydraulic iiuid used may be any fluid having a low coefficient ofviscosity such as the silicone oils.

It will be apparent that the embodiment shown is only exemplary and thatvarious modifications can be made in construction and arrangement withinthe scope of the invention as defined in the appended claim.

I claim:

In combination with a mine having a fuze, a mine protective devicecomprisinga cylindrical housing having an inner Wall, an intermedia-teannular Wall, an outer wall and an end wall, said end wall connectingsaid inner, intermediate and outer walls whereby an inner chamber and anouter chamber are formed for receiving a hydraulic fiuid therein, saidintermediate .Wall being apertured to provide restricted communicationbetween said inner and said outer chambers, there being a centralpassage provided through said housing by said inner wall, a guide sleevesecured in the lower end of said central 3,000,802 3 4 passage, anannular oatng piston slidabiy contacting to urge said pressure plate andsaid annular plate upsaid inner and said intermediate Walls, a pressureplate Wardly. having an annular fiange in telescoping contact with theaforesaid outer wall, said pressure plate being secured References Citedill the file 0f this Patent to the upper side of said piston, anactuating pin con- 5 UNTTED STATES PATENTS nected at one end to saidpressure plate, its other end 1702133 Remondy Feb 12 1929 being slidablyreceived in said guide sleeve and a spring surrounding said actuatingpin, said spring normally re- FOREIGN PATENTS acting between said guidesleeve and said pressure plate 796,981 Great Britain June 25, 1958

